As for thieno[2,3-d]pyrimidine compounds, several kinds of similar compounds have already been reported. For example, in Chemical Abstracts, 79, 61411n, 3,4-dihydro-3-(2-chlorophenyl)-2,6-dimethyl-4-oxothieno[2,3-d]pyrimidine was synthesized as methaqualone analogue possessing a hypnotic action. Their actions, however, are weak. In Japanese Patent Application Examined Publication (Kokoku) No. 42271/1972, there are disclosed hexahydro-3-lower alkyl-[1]benzothieno[2,3-d]pyrimidin-1-one compounds which have a central nervous suppresive action, and an antiinflammatory action. In Japanese Patent Application Unexamined Publication (Kokai) No. 68197/1977, there are reported 3,4-dihydro-6-(N,N-dimethylsulfamoyl-4-oxothieno[2,3-d]pyrimidine as a synthetic intermediate for the compounds possessing an anti-microbial action, anti-virus action, antibacterial action and plant growth-regulating action.
In the specification of Indian Patent No. 151496, some kind of thienopyrimidine compounds usable for hyperlipidemic treatment are reported: In Drugs of the Future, vol. 10, No. 2, p 1885, it is described that 2-chloromethyl-5,6,7,8-tetrahydrobenzo[b]thieno[2,3-d]pyrimidin-4(3H)-one which is encompassed in said Indian Patent is useful as a hypolipidemic agent.
In Arch. Pharm. vol. 309, pp. 908-913 (1976), it is reported that 2-aminomethyl-3-(2-methylphenyl)-5,6,7,8-tetrahydro(1)benzothieno[2,3-d]py rimidin-4(3H)-one compounds were synthesized as methaqualone analogues as mentioned above.
Meanwhile, the medicaments possessing an immunoregulating action have been in wide use recently for the prophylaxis or therapy of autoimmune diseases, the treatment of cancers, the amelioration of side-effects caused by anti-cancer agents, the therapy of infections diseases and so on. Particularly, as a medicament for chronic articular rheumatism which is one of the autoimmune diseases, the usefulness of the gold preparations for injections or oral administration is recognized, while such preparations have a defect of a number of side-effects. Accordingly, compounds having an excellent immunoregulating action and few side-effects have been demanded.